A Media Guide to Volcanoes

As many of you know, I tend to get a little irate when it comes to poor reporting on volcanoes in the media. Now, we can place a lot of the blame of the fact that most people have not had much experience talking scientifically (or at all) about volcanic activity, so instead they try to cope as best as they can with some wildly inaccurate terminology, descriptions and interpretations. Well, those excuses can no longer exist, as I’ve decided to make a handy media guide to volcanoes. Just like a sports team will hand out a guide of their team, players, statistics and more to reporters covering the event, this will hopefully help media who are trying to tackle reporting on volcanism to not make those common errors that plague so much of it. Enjoy.

Take home message: not all volcanoes look the same, so substituting volcano A for volcano B in a news report is a big no-no.

2. This is a caldera

Crater Lake in Oregon, formed by the catastrophic eruption and collapse of Mazama roughly 7,700 years ago. Image: NASA Earth Observatory.

Most calderas are formed by collapse rather than explosion. The explosive part of a caldera-forming eruption releases vast volumes of volcanic material, which then leaves empty space in the ground which causes the caldera to form. This doesn’t need to occur directly from an eruption — see Katmai 1912. So, remember caldera = collapse.

3. This is a crater (a feature on a volcano)

Ubehebe Crater in California, formed by an explosion when magma interacted with groundwater. Image: Erik Klemetti

Craters are formed by explosions, they are excavated (unlike a caldera, see above).

Things that can be erupted from a volcano:

Lava (molten rock — when underground, it is called magma), ash (tiny fragments of volcanic glass), lithics (chunks of rock that happen to get incorporated into the eruption), tephra (fine and coarse volcanic material), pumice (volcanic material full of air bubbles that is light enough to float in water), scoria (volcanic material full of air bubbles that doesn’t float), volcanic gases (mostly water vapor, significant carbon dioxide, sulfur dioxide, minor amounts of a lot of other stuff).

Things that aren’t erupted from a volcano:

Smoke (formed by combustion — there is no combustion in a volcanic eruption; see below), magma (see above “lava”), marshmallow fluff.

Eruptive plume from an eruption of Kanaga in Alaska. None of the material being erupted is smoke. Image: Public Domain.

Some useful things to know about volcanic eruptions and volcanoes:

Lava moves slowly (walking speed) most of the time. If your reports say that something came “rushing down the mountain,” it was likely either a pyroclastic flow (hot volcanic debris moving as an avalanche) or a lahar (volcanic mudflow).

Lava is hot, but it isn’t “boiling.” The bubbles in lava are gases escaping due to changes in their solubility (ability to remain dissolved).

Volcanic mudflows (lahars) aren’t hot. Most eyewitness accounts report that they are cold (thanks to all the water), but they are full of volcanic debris from the eruption and whatever material they have picked up along the way.

Volcanic plumes can be big. In fact, a volcano shooting ash “a mile into the sky” is actually pretty tiny. To even be considered a Plinian eruption, you need to be producing an ash plume that reaches at least 35-40 km or 21-25 miles up. So, does that mile-high (~5,280 foot/ 1.6 km) ash plume seem that impressive anymore?

An “active” volcano doesn’t necessarily mean it is erupting — if it is highly restless (earthquakes, etc.), then it can be considered active. If not, then the volcano is “dormant,” meaning it hasn’t erupted in years to thousands of years. An “extinct” volcano hasn’t erupted in likely over a million years. Remember, most volcanoes spend much if their existence not erupting.

Top 10 things that must be true* based on what I read in the media (*hint: they aren’t.):

I’ve added my corrections in italics.

There are only 7 volcanoes on earth: Yellowstone, Kilauea, St. Helens, Etna, Vesuvius, Eyjafjallajokull and Santorini. If another volcano erupts, it is “new.” There are literally thousands of active volcanoes worldwide, some of which are much more active than the “big 7.” In fact, there are quite a few that have produced significant eruptions in the past 10,000 years.

All every volcanologist does all day is try to figure out how to “predict” the next eruption. Predicting volcanoes is useful, but there are many other avenues of research that we pursue, such as rates of magma accumulation, the sources of magma in a volcano, how a pyroclastic flow disperses, the health hazards of volcanic smog and much, much more.

Every volcanic eruption will produce a dramatic climatic shift that will doom us all. Very few eruptions ever produce a noticeable change in the global climate — and even ones that seem like they would often have only very small effects.

Each new eruption is a sign that the volcano is ramping up to something dramatic, huge and unexpected. Volcanoes can do what they please and there are rarely patterns — beyond the very broad generalization that the longer between eruptions, the larger the eruption. However, that is misleading as there are countless examples of small eruptions from volcanoes that erupt infrequently.

Volcano can only “spew” and “belch” for material. Also, adding “super” or “mega” in front of thing makes it better. What is with these bodily functions? How about “expel” or “spreads” or “hurls?” (Come on folks, break out the thesaurus sometime.) As for “supereruption” and “supervolcano,” they are tired, somewhat meaningless hype words.

Every blip of volcanic unrest (earthquakes, deformation, degassing) means a horrific eruption is in the works. Active volcanoes are restless, so earthquakes, deformation and all the works can be expected between eruptions and during times that lead to no eruption. Panicking every time a volcano makes a noise is like pulling the fire alarm if you see a pack of matches on the ground.

If a volcano produced a giant eruption in its past, the current activity is definitely leading to something as big or bigger. Giant eruptions are the exception for volcanoes rather than the rule. You need a lot of accumulated, eruptible magma for a large eruption, and most research suggests that this is a tricky proposition. Yellowstone is an excellent example — sure, big eruptions, but also lots of little ones between the famous very large eruptions.

The “Ring of Fire” is the only important volcanic feature on the planet. I don’t know how many articles about volcanic eruptions I read that have somewhere in them a reference to the Ring of Fire, for example: “Indonesia straddles the “Pacific Ring of Fire,” an arc of volcanos and fault lines around the Pacific Basin.” The Ring of Fire is a bit of a contrivance, like “supervolcano.” The Pacific is rimmed by subduction zones that have volcanoes, but there are plenty of volcanoes elsewhere. It isn’t an important fact for us to hear every time.

Volcanoes sit atop a pool of liquid rock. This is a model that has fallen by the wayside. Most magmatic systems are a mixture of magma, crystals and gases — and those proportions change. They aren’t big empty vats that “fill” with magma before each eruption. Magma may intrude the “mush” under a volcano, but only at places like Kilauea is there a constant stream of almost entirely molten magma under the volcano.

Only eruptions that cause death have an effect on people. Many stories list the last eruption that caused fatalities. However, refugees are a major issue when it comes to volcanic activity that may or may not cause deaths directly related to an eruption.

Just as geologists have to strive to be better communicators of their science to the public, the media needs to be better at accurately describing and reporting on the natural world. When in doubt, talk to a volcanologist/geologist!